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LOANS HELD FOR INVESTMENT, NET - Credit Quality Indicators (Details) - USD ($) $ in Thousands | Jun. 30, 2022 | Dec. 31, 2021
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Credit Risk Profile of Real Estate Loans [Abstract] |  |
Principal balances outstanding | $ 9,660,907 | $ 9,244,661
2022 | 1,401,882 |
2021 | 1,762,601 | 1,839,501
2020 | 1,348,692 | 1,502,001
2019 | 1,141,101 | 1,289,329
2018 | 654,352 | 726,725
2017 and Prior | 2,616,737 | 878,430
2016 and Prior |  | 2,356,918
Revolving | 686,171 | 588,432
Revolving-Term | 38,582 | 46,426
Total Loans | 9,650,118 | 9,227,762
Pass |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |
2022 | 1,389,994 |
2021 | 1,760,706 | 1,828,115
2020 | 1,322,185 | 1,473,478
2019 | 1,046,787 | 1,174,655
2018 | 578,869 | 606,030
2017 and Prior | 2,423,540 | 752,529
2016 and Prior |  | 2,114,512
Revolving | 656,061 | 552,538
Revolving-Term | 27,282 | 29,902
Total Loans | 9,205,424 | 8,531,759
Special Mention |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |
2022 | 7,375 |
2021 |  | 6,003
2020 | 2,682 | 15,891
2019 | 62,113 | 54,365
2018 | 17,633 | 21,926
2017 and Prior | 62,218 | 23,775
2016 and Prior |  | 45,900
Revolving | 13,373 | 4,071
Revolving-Term | 1,314 | 2,033
Total Loans | 166,708 | 173,964
Substandard |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |
2022 | 4,513 |
2021 | 1,404 | 4,833
2020 | 23,825 | 11,011
2019 | 23,649 | 50,235
2018 | 57,098 | 97,994
2017 and Prior | 120,180 | 91,019
2016 and Prior |  | 196,506
Revolving | 16,737 | 30,823
Revolving-Term | 9,986 | 14,491
Total Loans | 257,392 | 496,912
Doubtful |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |
2021 | 491 | 550
2020 |  | 1,621
2019 | 8,552 | 10,074
2018 | 752 | 775
2017 and Prior | 10,799 | 11,107
Revolving |  | 1,000
Total Loans | 20,594 | 25,127
Total real estate loans |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |
Principal balances outstanding | 8,689,230 | 8,294,204
One-to-four family residential and cooperative/condominium apartment |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |
Principal balances outstanding | 691,586 | 669,282
2022 | 109,116 |
2021 | 111,694 | 129,679
2020 | 76,909 | 89,096
2019 | 68,125 | 82,568
2018 | 69,562 | 76,726
2017 and Prior | 195,127 | 80,365
2016 and Prior |  | 145,946
Revolving | 48,228 | 50,724
Revolving-Term | 12,825 | 14,178
Total Loans | 691,586 | 669,282
One-to-four family residential and cooperative/condominium apartment | Pass |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |
2022 | 109,116 |
2021 | 111,694 | 129,679
2020 | 75,873 | 86,028
2019 | 66,563 | 80,195
2018 | 68,407 | 75,354
2017 and Prior | 178,745 | 77,829
2016 and Prior |  | 129,276
Revolving | 47,383 | 49,878
Revolving-Term | 11,294 | 12,537
Total Loans | 669,075 | 640,776
One-to-four family residential and cooperative/condominium apartment | Special Mention |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |
2020 |  | 1,124
2019 | 332 | 335
2018 | 744 | 752
2017 and Prior | 1,519 | 334
2016 and Prior |  | 2,158
Revolving | 845 | 846
Revolving-Term | 737 | 747
Total Loans | 4,177 | 6,296
One-to-four family residential and cooperative/condominium apartment | Substandard |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |
2020 | 1,036 | 1,944
2019 | 1,230 | 2,038
2018 | 411 | 597
2017 and Prior | 14,863 | 2,202
2016 and Prior |  | 14,512
Revolving-Term | 794 | 894
Total Loans | 18,334 | 22,187
One-to-four family residential and cooperative/condominium apartment | Doubtful |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |
2018 |  | 23
Total Loans |  | 23
Multifamily residential and residential mixed-use |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |
Principal balances outstanding | 3,654,164 | 3,356,346
2022 | 770,923 |
2021 | 588,984 | 590,462
2020 | 340,244 | 353,747
2019 | 430,385 | 505,089
2018 | 162,829 | 183,616
2017 and Prior | 1,347,607 | 398,804
2016 and Prior |  | 1,309,248
Revolving | 12,372 | 14,555
Revolving-Term | 820 | 825
Total Loans | 3,654,164 | 3,356,346
Multifamily residential and residential mixed-use | Pass |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |
2022 | 770,923 |
2021 | 588,984 | 590,462
2020 | 327,826 | 341,206
2019 | 392,724 | 455,277
2018 | 128,595 | 151,226
2017 and Prior | 1,215,756 | 332,749
2016 and Prior |  | 1,145,609
Revolving | 12,372 | 12,277
Revolving-Term | 820 | 825
Total Loans | 3,438,000 | 3,029,631
Multifamily residential and residential mixed-use | Special Mention |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |
2020 |  | 11,040
2019 | 28,066 | 14,486
2018 | 9,696 |
2017 and Prior | 42,783 | 11,817
2016 and Prior |  | 26,252
Total Loans | 80,545 | 63,595
Multifamily residential and residential mixed-use | Substandard |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |
2020 | 12,418 | 1,501
2019 | 9,595 | 35,326
2018 | 24,538 | 32,390
2017 and Prior | 89,068 | 54,238
2016 and Prior |  | 137,387
Revolving |  | 2,278
Total Loans | 135,619 | 263,120
Commercial real estate ("CRE") |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |
Principal balances outstanding | 4,091,372 | 3,945,948
2022 | 459,162 |
2021 | 879,604 | 882,483
2020 | 788,722 | 851,450
2019 | 558,219 | 575,675
2018 | 357,667 | 370,839
2017 and Prior | 1,001,394 | 341,690
2016 and Prior |  | 874,439
Revolving | 40,757 | 43,183
Revolving-Term | 5,847 | 6,188
Total Loans | 4,091,372 | 3,945,947
Commercial real estate ("CRE") | Pass |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |
2022 | 456,248 |
2021 | 879,453 | 872,049
2020 | 784,966 | 848,694
2019 | 517,168 | 529,182
2018 | 321,183 | 306,360
2017 and Prior | 973,378 | 298,904
2016 and Prior |  | 815,238
Revolving | 40,757 | 43,183
Revolving-Term | 5,847 | 6,188
Total Loans | 3,979,000 | 3,719,798
Commercial real estate ("CRE") | Special Mention |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |
2022 | 2,914 |
2021 |  | 6,003
2020 |  | 1,024
2019 | 33,389 | 39,305
2018 | 7,128 | 18,983
2017 and Prior | 16,899 | 11,039
2016 and Prior |  | 17,438
Total Loans | 60,330 | 93,792
Commercial real estate ("CRE") | Substandard |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |
2021 | 151 | 4,431
2020 | 3,756 | 1,732
2019 | 7,662 | 7,082
2018 | 29,356 | 45,496
2017 and Prior | 11,117 | 31,747
2016 and Prior |  | 41,763
Total Loans | 52,042 | 132,251
Commercial real estate ("CRE") | Doubtful |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |
2019 |  | 106
Total Loans |  | 106
Acquisition, development, and construction |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |
Principal balances outstanding | 252,108 | 322,628
2022 | 8,413 |
2021 | 127,808 | 142,123
2020 | 59,294 | 77,427
2019 | 25,709 | 56,885
2018 | 17,543 | 36,956
2017 and Prior | 4,099 | 6,809
2016 and Prior |  | 774
Revolving | 8,788 | 1,066
Revolving-Term | 454 | 588
Total Loans | 252,108 | 322,628
Acquisition, development, and construction | Pass |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |
2022 | 8,413 |
2021 | 127,151 | 142,123
2020 | 59,294 | 76,259
2019 | 25,709 | 56,885
2018 | 17,543 | 23,456
2017 and Prior | 4,099 | 6,809
2016 and Prior |  | 774
Revolving | 8,788 | 1,066
Revolving-Term | 454 | 588
Total Loans | 251,451 | 307,960
Acquisition, development, and construction | Special Mention |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |
2020 |  | 1,078
Total Loans |  | 1,078
Acquisition, development, and construction | Substandard |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |
2021 | 657 |
2020 |  | 90
2018 |  | 13,500
Total Loans | 657 | 13,590
Commercial and Industrial ("C&I") Loans |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |
Principal balances outstanding | 960,888 | 933,559
2022 | 54,268 |
2021 | 54,511 | 94,754
2020 | 83,523 | 130,281
2019 | 58,663 | 69,112
2018 | 46,751 | 58,588
2017 and Prior | 68,510 | 50,762
2016 and Prior |  | 26,511
Revolving | 576,026 | 478,904
Revolving-Term | 18,636 | 24,647
Total Loans | 960,888 | 933,559
Commercial and Industrial ("C&I") Loans | Pass |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |
2022 | 45,294 |
2021 | 53,424 | 93,802
2020 | 74,226 | 121,291
2019 | 44,623 | 53,116
2018 | 43,141 | 49,634
2017 and Prior | 51,562 | 36,238
2016 and Prior |  | 23,615
Revolving | 546,761 | 446,134
Revolving-Term | 8,867 | 9,764
Total Loans | 867,898 | 833,594
Commercial and Industrial ("C&I") Loans | Special Mention |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |
2022 | 4,461 |
2020 | 2,682 | 1,625
2019 | 326 | 239
2018 | 65 | 2,191
2017 and Prior | 1,017 | 585
2016 and Prior |  | 52
Revolving | 12,528 | 3,225
Revolving-Term | 577 | 1,286
Total Loans | 21,656 | 9,203
Commercial and Industrial ("C&I") Loans | Substandard |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |
2022 | 4,513 |
2021 | 596 | 402
2020 | 6,615 | 5,744
2019 | 5,162 | 5,789
2018 | 2,793 | 6,011
2017 and Prior | 5,132 | 2,832
2016 and Prior |  | 2,844
Revolving | 16,737 | 28,545
Revolving-Term | 9,192 | 13,597
Total Loans | 50,740 | 65,764
Commercial and Industrial ("C&I") Loans | Doubtful |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |
2021 | 491 | 550
2020 |  | 1,621
2019 | 8,552 | 9,968
2018 | 752 | 752
2017 and Prior | 10,799 | 11,107
Revolving |  | 1,000
Total Loans | 20,594 | 24,998
Other Loans |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |
Principal balances outstanding | 10,789 | 16,898
Other Loans | Credit Risk Profile |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |
Principal balances outstanding | 10,789 |
Other Loans | Performing |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |
Principal balances outstanding |  | 16,533
Other Loans | Performing | Credit Risk Profile |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |
Principal balances outstanding | 10,658 |
Other Loans | Non-Accrual |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |
Principal balances outstanding |  | $ 365
Other Loans | Non-Accrual | Credit Risk Profile |  |
Credit Risk Profile of Real Estate Loans [Abstract] |  |
Principal balances outstanding | $ 131 |

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